We make a few sub-directories recursively, in particular
$(TARGET_DIRS).
For goal "all", we do it the nice way: "all" has a prerequisite
subdir-T for each T in $(TARGET_DIRS), and T's recipe runs make
recursively. Behaves nicely with -j and -k.
For other goals such as "clean" and "install", the recipe runs make
recursively in a for loop. Ignores -j and -k.
The next commit will fix that for "clean" and "install". This commit
prepares the ground by renaming the targets we use for "all" to
include the goal for the sub-make. This will permit reusing them for
goals other than "all".
Targets subdir-T for T in $(TARGET_DIRS) run "make all" in T. Rename
to T/all, and declare phony.
Targets romsubdir-R for R in $(ROMS) run "make" in pc-bios/R. Default
goal is "all" for all R. Rename to pc-bios/R/all, and declare phony.
The remainder are renamed just for consistency.
Target subdir-dtc runs "make libbft/libfdt.a" in dtc. Rename to
dtc/all, and declare phony.
Target subdir-capstone runs make $(BUILD_DIR)/capstone/$(LIBCAPSTONE)
in $(SRC_PATH)/capstone. Rename to capstone/all, and declare phony.
Target subdir-slirp runs "make" in $(SRC_PATH)/slirp. Default goal is
all, which builds $(BUILD_DIR)/libslirp.a. Rename to slirp/all, and
declare phony.
Backports commit 3b8593eeaa5778ae118f0cc2837e615acd13baeb from qemu